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Efficient Construction of Drug-like Bispirocyclic Scaffolds Via Organocatalytic Cycloadditions of α-Imino γ-Lactones and Alkylidene Pyrazolones
Published on: February 7, 2019
Intramolecular cycloaddition in 6,6-spiroepoxycyclohexa-2,4-dienone: simple aromatics to (+/-)-platencin
Vishwakarma Singh1, Bharat Chandra Sahu, Varsha Bansal
1Department of Chemistry, Indian Institute of Technology Bombay, Mumbai 400 076, India. vks@chem.iitb.ac.in
Abstract:
A formal total synthesis of platencin from a simple aromatic precursor is described. Transformation of the aromatic compound into reactive spiroepoxycyclohexa-2,4-dienone and intramolecular cycloaddition are the key features of our methodology. 2-Hydroxymethyl-6-(3-hydroxy-hex-5-enyl)-phenol was oxidized with NaIO(4) to give a dimer that, upon a retro-Diels-Alder reaction, generated the spiroepoxycyclohexa-2,4-dienone that underwent intramolecular Diels-Alder reaction to give a tricyclic adduct having a core structure of platencin and appropriately disposed functional groups in a single step. Reduction of the double bond present in the ethano-bridge, manipulation of the oxirane ring and introduction of a double bond in the six-membered ring furnished a tricyclic intermediate which has already been converted into platencin.
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